Electrical musical instrument



ELECTRICAL MUSICAL INSTRUMENT i# l V SQIL-'t' IIIITLIM', i

March 14, 1950 J. M. HANERT ELECTRICAL MUSICAL INSTRUMENT 3Sheeizs-Sheet 2 Filed Feb. 16, 1948 MAMMA J. M. HANERT ELECTRICALMUSICAL INSTRUMENT 3 Sheets-Sheet 5 w ANS March 14, 1950 Filed Feb. 16,1948 Patented Mar. 14, 1950 ELECTRICAL MUSICAIIINSTRUMENT John M.Hanert, Park Ridge, Ill., assignor to Hammond Instrument Company,Chicago, Ill., a corporation of Delaware Application February 16, 1948;Serial No. 8,680

(Cl. SLi- 1.24)

7 Claims.

My invention relates generally to electrical musicaly instruments andmore particularly to improved key-operated control circuits for suchinstruments.

In electrical musical instruments played in non-reverberative rooms, itis desirable that the tones producedv have a gradual decay after therelease of the key, thereby to produce the equivaient of thereverberation eiect. Since it is the depression of the key whichnecessarily determines the pitch of the tone to be sounded, the releaseof the key leaves indeterminate the pitch of the decay portion of thetone unless there is `incorporated some mechanism or circuit in theinstrument which is capable of remembering the last key depressed untilanother key is depressed. While this may be accomplished mechanically bythe usefof various types of latch and bail mechanisms, such mechanismsusually require the use of a large number of parts which must be madewith precision .and are thus costly, are subject to wear, and may becomenoisy in operation.

Itis thus a primary object of my invention to provide improved means forcontrolling an electrical musical instrument to secure thereverberationeil'ect by causing the tones produced to decay graduallyafter the release of the key which was depressed to cause the .tone tosound.

A further object is to provide van improved key controlled circuit foran electrical musical instrument which has means for causing a tone`to'be sounded `for a predetermined time after the re lease of the key.

A furtherv Objectis to provide an improved electrical vmusicalinstrument in which yrelays are employed in the key circuits and inwhich each of the relays is provided with a holding circuit and isadapted to control the pitch of the tone produced.

Other objects'will appear from the following description, referencebeing Vhad to the accompanying drawingin which:

Figure l is aschematic'wiring diagram ofan exemplary form of -theinvention;

Figures 2, 3 and 4 are similar diagrams of modified forms oftheinvention.

For purposes-of illustration the invention'will be described asincorporated in an instrument of the melody type, that is, one which iscapable of playing but a singlevnote at one time andyis provided with agenerating system for producing the notes of the pedal register of anorgan, yor for use as a piano accompanimentinstrumentzof the ltypeshowninmyprior Patent No. 2,357,191.

The instrument comprises a plurality of pedals CO to. Cl for theco-ntrol of tones having fundamental frequencies of 32,703 to 65,406 C.P.S. All thekeys except Cl are arranged upon depression ,to close.y aswitch A and open a switch B, the key CI operating to close a switch Aonly. Each of the switches A (except the switch A for key CO) is adaptedupon closure to complete a circuit through a winding of a relay l0,which, upon being energizedcloses a switch C and opens a switchD.

:Energization of the relays is accomplished through Aa circuit'includinga source of `potential indicated as a terminal +24 v. connected to aconductor IZ'through a relay Winding Ill. Upon closure of a switch A(except for key CO) a circuit is completed toa relay I0 which has onegrounded terminal. Upon energizationof the relay l0 its switch Cv closesto complete a holding circuit which connects the ungrounded terminal ofthe winding of relaywl through this switch C and theV seriesofswitches Bassociated with all keys of` lower pitch, the circuit being thuscompleted to the +24 v. terminal.

It-will be apparent from the circuit diagram that .as a resultof thecompletion of the relay holding circuits through the switches B oi lowerkeys, that depression of any key lower than that previously depressedwill open the holding circuit of. the .previously depressed key, whereasdepression cfa keyhigher ,than the previously depressed keywillnotunlock the holding circuit established by the previouslydepressed key.

VThe switches D are connected in series, the highestkey Cl having itsswitch D connected to ground. The junctions intermediate the switches Dare connected to a conductor I6 through parallelucapacitors CI8. Thus,depending upon which of the relays ID is energized none, or any othernumben-or all of the capacitors CIS will be connected in parallelbetween the conductor 1G and ground andA will thus be in parallel with acapacitor C29 which forms part of a parallel resonant mesh including avariable tuning inductance L22, thelatterzbeing coupled to a feedbackinductance L24. The `conductor .i6 -is connected through a grid leakresistor R26 and a capacitor C28 with the'grid of pentode 32, thecathode and suppresser grid of vwhich are connected to ground throughthe inductance L24. Operating potentials are supplied to the screen gridand plate of the pentode '32 from a suitable source of potentialindicatedas a terminal +B through a Voltage dropping resisto-r R36 and aload resistor R38 respectively. The-screen grid is connected to groundthrough a filtering capacitor C39. The pentode 32 with its associatedcircuits thus comprises an oscillator, the frequency of operation ofwhich is determined by the number of capacitors CI8 which are connectedin parallel with its capacitor C20. rIhe oscillator is initially tunedby adjustment of variable inductance L22.

The output of the oscillator pentode 32 is coupled to suitable tonecontrols through a blocking capacitor C42. The tone controls maycomprise any suitable types of selectively coupled resonant circuitshaving different frequency response characteristics and controllable byselectively operable switches, such as shown, for example, in my priorPatent No. 2,276,390. The signal, as modied by the tone controls, isimpressed upon the control grid of a phase splitting trode 44 having itscathode connected to ground through series resistors R46 and R41. Thejunction of these two resistors is connected to the control grid througha grid resistor R48. Plate voltage is supplied through a load resistorR50 connected to a suitable source of potential indicated as +B, and theplate is coupled to the control grid ci a control pentode 52 through ablocking capacitor C54.

In a similar manner the junction between the resistors R46 and R41 isconnected to the control grid of a control tube 53 through a blockingcapacitor C55. The suppressor grids of the pentodes 52 and 53 areconnected to their cathodes while the screen grids are connectedtogether and have a suitable operating potential im pressed thereonthrough voltage dividing resistors R60, RSI and variable volume controlresistor R62 connected between a +B terminal and ground. The cathodes ofthese pentodes are connected to ground and are connected to a junctionpoint 64 through a decay capacitor C66, which may have a capacitor C68connected in parallel therewith upon closure of a manually operableswitch 10. The terminal 64 is connected to the control grids of pentodes52 and 53 through grid resistors R12 and R13 respectively, and anegative cut-off bias is normally supplied to the grids through R'i4which is connected between the terminal 64 and a suitable cut-oifbiasing potential source indicated as a terminal v. The terminal 64 isconnected through a resistor R16 and conductor 18 to one pole of aswitchforming part of relay I4, the other pole of the swtich 80 beingconnected to ground.

In View of the fact that the key CO does not have a relay I0 associatedtherewith, its switch A is adapted to connect a suitable compensatingload resistor R82 between conductor I2 and ground when the switch isclosed, the resistance of R82 being comparable to that of the winding ofa relay I0.

The relays I 0 and I 4 preferably have anti-spark resistors (not shown)connected in parallel therewith to prevent excessive sparking at thecontacts of switches A.

The pentodes 52 and 53 are supplied with plate voltage from a terminal+B through load resistors R84 and R85 and the output of these pentodesis coupled to the input of a push-pull amplier 86 through blockingcondensers C88 and C89 respectively. A speaker 90 is coupled to theoutput of the power ampliner 86.

From the foregoing it will appear that when any one of the keys CO# toCI is depressed the closure of switch A will result in the energizationof its associated relay I0 and the opening of the switch B will cut offthe supply of energizing current to all relays I0 associated with keyshigher in the musical scale. The closure of the switch A will alsoresult in energization of relay I4 with the resultant closure of switch80, thereby connecting terminal 64 to ground through resistor R16. Theresistors R14 and R16 thus form a voltage divider, determining thepotential on the terminal 64. The potential on this terminal willthereioer rise gradually as the capacitor C66 is discharged, and thegain of the pentodes 52 and 53 will therefore increase gradually frombelow cutoff to a substantial value suicient to transmit the signal atmaximum amplitude. The rate of attack will of course depend upon therelative values of R16, R14 and C66 (also C58 if switch 10 is closed)and the tone will thus be produced by the speaker 90 at graduallyincreasing intensity, the maximum value of which may be controlled bythe volume control variable resistor R62.

Upon energization of the relay I0 associated with the depressed key itsswitch C closes and switch D opens. Closing of the switch C establishesthe holding circuit previously described, while the opening of theswitch D determines the number of capacitor CIB which are in parallelwith the capacitor C20 in the tuning circuit of the oscillator pentode32. The values of the capacitors CI8 are so chosen so that theoscillator will oscillate at a frequency corresponding to the pitch ofthe depressed key.

Upon release of the depressed key the relay I4 is deenergized, openingthe switch 80 and permitting the potential of terminal 64 to driftgradually to its cut-off bias potential of -60 volts, the rate at whichthis is accomplished depending mainly upon the relative values of R14and C66 (and C68 if switch 10 is closed). The relay I0 associated withthe depressed key will however be maintained in energized conditionuntil another key is subsequently depressed. If the second key depressedis of higher pitch than the rst depressed key the relay associated withthe first depressed key will remain energized.

i Thus, for example, if the keys CO-tto Cl were depressed in succession,all of the relays I0 would eventually be locked in an energized state.

By virtue oi` the fact that this is a possibility it is necessary thatthe source of current for the operation of these relays be adequate topermit this to take place. On the other hand, if the keys aresuccessively depressed commencing with the key CI and ending with thekey CO, the depression of each key will open the holding ciri cuit forthe relay of the prior depressed key and thus the load on the +24 v.current source will be limited to that required for the energization ofbut one of the relays at any one time. In playing a musical compositionit will be seldom that more than three or four of the relays I0 will besimultaneously energized.

The switches D are intended to be representative of any switch in anymusical instrument which controls the selection of the pitch to besounded. For example, the switches D, instead of being opened upon theenergization of their associated relays, might be arranged to be closedthereby, and the switches might then be arranged to eiTect the selectiveenergization of solenoid-operated valves controlling the wind supply toorgan pipes. They might also be used to connect electrical generators(e. g. of the type shown in Hammond Patent 1,956,350) to a suitableoutput circuit, or to control the energize.- tion of other types ofelectrical tone signal genassassin 5 oratore. Iny utilizing .the.-keyacontrolcircuits@ of;A the invention withf the. fpipe organ :andothervin. struments it may not be necessary to providefthe.. relay I4..Instead the conductor IZwmight be. connected directly tothe operating.potential source +24 v.

The invention ishof greatest utility when,v eme ployedinconnection withthe bass register. tonesy oan-instrument since the-reverberation effectis not as essential.inftheproduction 01E-.treble register tones.` In the.basse register a longdecay of` the tones will produce the effect .ofalong reverberation time. The duration of the decaytime may be.suited tothe, enclosure in which thev instrument is to bey played by vproperselec7 ionofzthe valuesof C66,l C68'and`R114.,

In the `circuit shown in fFig.' 1 the highest of. aplurality ofsimultaneously depressed keys de termines the frequency to which theoscillator istuned.v Insorne instances it may be preferred to have thelowest of several simultaneously de-., pressed keys determine thefrequency generated.V The .latterresult maybe accomplished by theycircuit shown in Fig. 2;

In Fig. 2, each of the keys CO to CI, upon depressiom. closes a switch.IDI; and in addition eachof the. keys CO# to yCI opens a switch |02.Closure of aswitchIUI. associated with keys C0 to. BO connects` aconductor |03 toground througha relay winding |il4,associatedwith the.depressed key, whileclosure of switch |0| asso.- ciated. with key CIconnects conductor |03v to.. grou-nd` through a compensating` resistorRISE; The-conductor. |03 zis connected' to .a suitable source of.current, indicated as -a +24 v. terminal, 'through a relay: winding|08;`

Each of the relays |04 isadapted, upon energization, to close a switchIi! `to. complete a holding circuit. It will be noted that theholdingcircuit forl each of the relays |04: includes in series theswitches |02 for all of the higher pitch keys, andnvill therefore bebrokenr upon clefv pression of any higher key'.,

Each of relays |04, upon energization, also closes-a switch ||2,eiective to tunetheoscillator-to the pitch corresponding to the lowestofA severalv simultaneously depressed keys. Each ofr the switches I I2has one pole connected to ground and theother pole 'connected to oneof aseries of.; junction points between a series oflcapacitors CII-L Thelast capacitorV CI I4 ofthe series is connected to ground lso thattheseries is effectively; in parallelwith capacitor C2 0f and variable;inductanceLZZ. These capacitors, together with the inductance L22 formthe resonant tuning cir-Y cuit of an oscillator similar to thatdescribed with` reference to Fig. 1. The `same reference characters havetherefore been applied,v to the corresponding parts of the twooscillators.

The oscillator of Fig. 2 has its output coupled to anl output system. II5v similar topthatshown ingreater detail in Fig. l, and the signalsfrom this output systemv are translated into sound by a speaker H8. Therelay |08 operatesa switch iin-(corresponding to switch l8|) of Fig.1).to control the attack and decay of the tone signalstransmitted*by-thel output system I6.

The instrument shown-'in Fig.` 2 operates `in substantially the sa-memanner as that showny in Fig. 1 except that in the apparatus oi Fig,` 2the. lowestV of several simultaneously depressed keys orpedalsdeterrnines they pitch of the tone produced. If a numberof notesare, played commencing atthe high end of thescale; `the relaylassociated Awith thepvvhigher key` will remain in lockedconditionvafter. such keyis released,pbut;

on-the otherhand,if:.a series ofkeys areplayed.-

commencing at the lower end of the scale, each-` higher key uponitszdepression will open the circuitsupplying energizing current for allthere-- lays |04. associated with the lower keys..

The modified viormsof the invention shown; in theFigs. 3 and 4havemanyl'parts identical.

fwhen'moved to dotted line position makeconi nection with one ofi theoutputterminals oi a tone frequency vgenerator |32; whichr may; bef ofthe phonic wheel type, as shown inv thepatentgto Laurens Hammond No.1,956,350.. The-generator;

|32may also bean' electronic oscillator, a vibra,u

tory reed `with electric'pickup, or of anyv'othersuitable type,preferably generating a. `complex wave. The switch |310; for the vnoteC| isfcone nected to anV amplifier |34whicl'1-v may. includev tone,attack, decay; andy volume controls, the

output of the amplierbeing fed to `a speaker |3,6;

From the foregoing, it -Wll be clear that the highest of a plurality ofdepressed keys. will,

through operation loi' its associated .switch |30,

connect its` generator4 |32 .totl the amplifier and also open thecircu-itbetween the ampliiier |34 and all ofthe generators |32associated with.

any of the keysand will cause the ampliiier toy transmit the` signalwith vthe' desired attack, and upon release of thekeys, the switch 80will open and the gain of the-amplifier will decrease at a.predetermined rate to` provide the desired decay.

It will be noted however, that the highest energized relay I0 willremain locked so that its associated generator will continue to supplythetone signal to the amplifier throughout this decayv period.

In theembodiment oi the invention shown in 55. Fig. 4, the relayoperated-switches Dare con-V nected to control thev supply of energizingcur-r rent to the plates of vacuum tube oscillators;

The relay operated switch 80, when closed, con-- nects a source of platecurrent indicated as B+ 60 to a conductorr |40 which is connected to onethrough a grid bias resistor R|54 anda bypass.,

capacitor CISG., the other terminal of the in ductance L|52 beingconnectedv to ground. A. 7 5' capacitor C|58 is connected inparallelwiththa the, same reference; characters have therefore Theswitches |30 are. connected in serieswwhen in full line position, and..

The switches |3,.

d' inductance Ll52, and the cathode of the triode |48 is connected to atap |60 on the inductance L|52.

The output of the oscillator |44 is transmitted to an amplifier |62through a blocking capacitor C|64 and a resistor Rl 66. The amplifier|62 may include the usual tone quality and volume con* trols and has itsoutput connected to a speaker |65. The switch 8!) is provided with adashpot |66 which permits the switch 80 to close rapidly but delays theopening of the switch after its relay winding I4 has been deenergized,for an interval in the order oi 1.5 seconds.

From the foregoing it will appear that when ever one of the keys isdepressed, its associated relay 4D will be energized and the switch C ofthis energized relay will close to establish a holding circuit. Also theswitch D of the energized relay ||l will be moved from iull to dottedline position and thereby supply plate current to the associatedoscillator and cause the latter to commence oscillating. The capacitors(H50, together with their associated resistors R|42 and RMS, operate asfilters to reduce transients which may be caused by the closure of theswitches D. It will be understood that there is an oscillator, such as|44, associated with each of the playing keys and that the outputs ofthese oscillators are connected in parallel to the amplifier |62. Theseoscillators are intended to be representative of any musical tonegenerator, electrical or mechanical, the operation of which may becontrolled by the completion of a circuit supplying electrical energythereto. For example, electromagnetically operated valves controllingthe sup ply of wind to organ pipes may be substituted for theoscillators.

In playing any of the instruments disclosed the player may, without anyattention upon his part, merely by depressing the pedals or keys in astaccato manner, cause the tones to persist through the desired decayperiod and thus produce a desirable reverberation elect. If the keys aredepressed in a legato manner, the tones will have the usual intensityenvelopes i sustained organ tones. Since, in the forms of the inventionshown in Figs. l, 2, and 3, the amplifier is cut off when no keys aredepressed, the depression of a key or pedal does not, as a result oi theclosure of its switch D, i3d, or |I2, produce any undesirable transientsin the signal supplied to the speaker, and thus key clicks or thumps arenot present in the tone produced.

While I have shown and described particular embodiments of my invention,it will be apparent to those skilled in the art that numerousmodifications and variations may be made in the form and constructionthereoi", without departing from the more fundamental principles of theinvention. I therefore desire, by the following claims, to includewithin the scope of my invention all such similar and modified forms ofthe apparatus disclosed, by which substantially the results of theinvention may be obtained by substantially the same or equivalent means.

I claim:

1. In an electrical musical instrument having electrical musical tonesignal generating means, a plurality of playing keys; a relay associatedwith each of said keys; a circuit for each of the keys including aswitch operated by the key, the winding of its associated relay and asource of energy in series; a holding circuit for each of said relays,each holding circuit including in series a switch operated by the relay,a source of energy, and switches opened respectively by operation ofkeys for notes lower in the musical scale; switches operable by therelays respectively to determine the pitch of the tone signal providedby the generating means; and an output system including an amplifier andelectroacoustic translating means, said amplier having means to controlits gain in response to depression of any of said keys thereby to causethe sounding of a tone with gradual attack.

2. In an electrical musical instrument havingY an output systemincluding an amplifier electroacoustic translating means, an electricalmusical tone signal generating means capable of providing signals of thefrequencies of the notes of the musical scale, and a plurality ofplaying keys; the combination of a switch A associated with each key andclosed upon depression thereof, a switch B. associated with each key andopened upon depression thereof; a relay associated with each of thekeys; a source of electrical energy; an energizing circuit for eachrelay including in series the Switch A, the relay winding, and thesou;cc; a pair of switches C and D respectively closed and opened uponenergization oi the relay; a holding circuit for each relay including inseries the relay winding, the source, and all of the switches Bassociated with keys of lower pitch; means responlsive to the operationof switch D to cause the generating means to supply to the output systema signal oi frequency corresponding to the pitch oi" the depressed key;and means associated with the ampliiier and controlled in common by allof the keys to render said amplifier ineffective to transmit signalswhen none of the keys is depressed and to cause the amplier to transmitthe signal with gradual attack upon depression of any key and withgradual decay upon release of the key.

3. In an electrical musical instrument of the melody type having anamplifier including a terminal, the potential of which determines itsgain, an electroacoustic translating means coupled to the amplifieroutput, and a tunable oscillator coupled to the input of the amplifier;the combination of a keyboard comprising a plurality of playing keys, apair ol` Switches A and B associated respectively with each of saidkeys, switches A being closed and switches B beine opened upondepression of the associated key; a key relay associated with each key,each key relay including switches C and D, switch C being closed whenthe relay is energized; a control relay operating a switch 80 whenenergized; a mesh including switch 8S and connected to the said terminalof the amplier to cause the potential on the terminal to change in adirection to cause gradual increase in the gain of the amplifier whenthe switch is closed and to cause the potential on the terminal tochange gradually in the opposite direction when the lswitch is opened; acircuit including in series a sour-ce of energy, the winding of thecontrol reay, and said switches A in parallel; means controlled by theswitches D to tune the oscillator to the various musical tonefrequencies; and a holding circuit ior each of the key relays, each ofthe holding circuits including all the switches B associated with keysnearer one end of the keyboard than the key with which the particularrelay is associated.

4. In an electrical musical instrument having electrical tone signalgenerating means; a keyboard comprising a plurality of playing keys; arelay associated with each key; a circuit for each of the keys includingin series a switch operated by the key, the winding of its associatedrelay, and a source of energy; a holding circuit for each of the relays,each holding circuit including in series a source of energy, a switchclosed by the relay, and switches opened respectively by the depressionof keys nearer one end of the keyboard than the key with which the relayis associated; switches operated respectively by the relays, the switchof the relay associated with the key farthest from `said end of thekeyboard being effective to determine the pitch of the tone signalprovided by the generating means; and an output system for `amplifyingthe tone signals provided by the generating means and translating theamplied signals into sound.

5. The combination set forth in :claim 4 in which there is provided anadditional relay energized upon the operation of any of the keys, and inwhich this relay controls the intensity envelope of the tones producedby the translating means.

6. In a musical instrument having musical tone producing means; akeyboard comprising a plurality of playing keys; a relay associated witheach key; a circuit for each of the keys including, in series, a switchoperated by the key, the winding of its associated relay, and a sourceof energy; a holding circuit for each of the relays, each holdingcircuit including in series a source of -energy, a switch closed by therelay, and switches opened respectively by the depression of keys nearerone end of the keyboard than the key with which the relay is associated;and additional switches operated respectively by the relays, and meanscontrolled by the additional switches to cause the tone producing meansto produce a tone of a pitch corresponding to that of the key by whichit is controlled and when a plurality of keys are operated at the sametime to produce a tone of the pitch corresponding to that one of theoperated keys which is farthest from said end of the keyboard.

7. The combination set forth in claim 6`in which there is provided anadditional relay energized upon the operation of any of the keys, and inwhich this relay controls the intensity envelope of the tones emitted bythe tone producing means.

J OHN M. HANERT.

No references cited.

